Abstract
Potential antioxidant properties of an aqueous extract of the edible red seaweed Gracilaria tenuistipitata (AEGT) against oxidative DNA damage were evaluated. The AEGT revealed several antioxidant molecules, including phenolics, flavonoids and ascorbic acid. In a cell-free assay, the extract exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity that significantly reduced H2O2-induced plasmid DNA breaks in a dose-response manner (P < 0.001). The AEGT also suppressed H2O2-induced oxidative DNA damage in H1299 cells by reducing the percentage of damaged DNA in a dose-response manner (P < 0.001) as measured by a modified alkaline comet-nuclear extract (comet-NE) assay. The MTT assay results showed that AEGT confers significant protection against H2O2-induced cytotoxicity and that AEGT itself is not cytotoxic (P < 0.001). Moreover, H2O2-induced cell cycle G2/M arrest was significantly released when cells were co-treated with different concentrations of AEGT (P < 0.001). Taken together, these findings suggest that edible red algae Gracilaria water extract can prevent H2O2-induced oxidative DNA damage and its related cellular responses.
Highlights
The red algal genus Gracilaria is distributed worldwide and is the main source of large scale production of food grade agar and phycocolloids [1]
The hypothesis was tested by using hydrogen peroxide (H2O2) as a DNA damaging agent [19] to examine the antioxidative properties of aqueous extracts of G. tenuistipitata (AEGT) and its role in recovery from plasmid and cellular DNA damage, cytotoxicity, and cell cycle arrest
These results indicate that AEGT stabilizes DNA molecules by neutralizing oxidative DNA damage by H2O2
Summary
The red algal genus Gracilaria is distributed worldwide and is the main source of large scale production of food grade agar and phycocolloids [1]. Because Taiwan can produce more than 30,000 tons of Gracilaria annually, this inexpensive algae is an important aquaculture species [1]. Bioactivities of marine algae of the genus Gracilaria have been extensively studied [8]. The many health-promoting properties of genus Gracilaria seaweed extracts include the anti-hypercholesterolemic properties of G. tenuistipitata [9], the antioxidative properties of G. tenuistipitata [10], G. edulis [11], G. salicornia [12], G. birdiae and G. cornea [13], the anti-inflammatory properties of G. verrucosa [14]. The antioxidant properties may be helpful for modulating the effects of reactive oxygen species (ROS) generated by cellular metabolism or environmental factors. This study hypothesized that Gracilaria extract has the potential to modulate H2O2-induced DNA damage and its related cellular responses. The hypothesis was tested by using hydrogen peroxide (H2O2) as a DNA damaging agent [19] to examine the antioxidative properties of aqueous extracts of G. tenuistipitata (AEGT) and its role in recovery from plasmid and cellular DNA damage, cytotoxicity, and cell cycle arrest
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